Method of heat-treating steel castings.



i. G. KRANZ. METHOD OF HEAT TREATI APPLICATION FILED N0\7.7,1908. 95 1,368.

l f f. WA

mm tft. ICRWF SHARON, PENNSYLVANIA, ASSGNOR TQ THE NATINAL eation of Letters Pate:

pjncation filed November i?, 1908. Serial No. G'Li l have found that low cai-hou steel cast ings particularly cast. steel coupler kluufklesv and coupler heads and shauks which contain less than tive-tenths ot' one per rent. earhou, can be greatly improved in quality and made to stand more rigid tests than heretofore, il' they are subjected to a. heat lreatuwul. in

which the Castings are first heated lo about i a cherry red heat namely, to about 13009` .14000 F.. then carried at a uniform rate through boilingr Water, in which they remain for a uniform and specific time, aud are then carried at a unitorm rale and tor a uniform time through a healing' chamber, I;

in which they are reheated to about 700" or 800 Fahrenheit, the heat communicated to the castings in the.reheatingf chamber being less than a red heat. `When treated in this Way, the product oi the steel foundry is made uniform and itsquality is greatly improved.

In the practice of my invention, "l employ a Vessel or tank continuing water, which is rapidly brought to a boilingcondition in auf suitable manner, and is maintained in lioiling condition by the passage of the hot listings through it. so as to he of uuiform temperature, andl employ; in oonjunction with such tank or vessel, a reheatmg furnace. A conveyor leads through the vessel of water and through the reheating furnace and carries the. castings therethrough at a uniform rate so that the dura.- tion of the cooling and reheating o erations upon the castings can be accurate y deter mined and uniform results produced.

It is easy for the operator to time the travel of the castings through the' water to the desired rate, the purpose heiney lo cool the castings therein to a temperature less than 700o F., preferably less than L'LOGO l1". It' is not necessary, however, that the castings should be cooled down to the temperature of the water through whieh they pass. he rate of travel will, ot' course, vary with the shape and size ot 'the castings. A. casting' haring' a large surface area in proper1- tion to its weight will cool more rapidly when in contactwith the water than ay cast ing' whose surface'. area in proportion to its weight is less.

in thel drawings, i? represents a furnace in whirh the castings haring been taken, from the molds are plaeed and hrougjljl'it to a cherry red hea t. 'lhey are then removed frointhis furnace and dropped or otherwise placed 'on a conveyor 3, which may he au ordinaryT chain eonreyer. and leads down and into an open tank .of wa-'ler l. carrying' the castings through the water and iuuuersing there therein during' their passage through the tank. The conveyor passes up from the tank and, as shown, is arranged to diseharo'fl onto a second conveyor o. which pas is through a rehealing furnace 5, in which the Castings are reheated to the degree ahoye speciied, and al' the end of the l'urnaeethey are discharged and at'ler coolingr are ready for use.

:instead of water, oil or other liquid may be employed, water being },1'eterred, ho.v

i ever, from the standpoint ot cost.

I claim:

l. rlhe method herein described, which consists in treating low Carbon steel castings oy heating the saine to o about a cherry red heat, namely, about lROOLlIlOO" F., then subjecting' them to a boiling' liquid for a regulated time, and thon wheaiuothem to a degree less. than red heal.

Q. The method herein described ot treating low carhou vsteel castings, which consists in heating them to or about a eherry red heat, namely, about. 15000-1400 lv., then carrying them at a regulated speed a retreating Chamber wherein they are reheated to a temperature below red heat.

irl. The method herein described ot` treat ing low carhon steel castings, whirh consists in heatingthem to or ahout a cherry red heat, then carrying); them at a-regulated Speed successively through boiling` liquid and through a reheatiug chaiuher wherein they are reheated to a temperature below red heat.

. The method herein described or" treatbeat,- namely3 about 13000-14000 Ik, then v wwwa o'wparbon steel. castings, which consist; In testimonyv whereof, I have hereunto m heatmg them or about a cherry red met my hand. cooling hem to .a empemture below 700 F. WILLIAM Gf KRMIZ :i by subjec'tmg them 'to a hqunld for a mgm Wlnesses:

a'ed tune, :md han rehefmng them m a THGMAS W. BAKEWELL vigre ess than red hea. H, M., CORWIN. 

